19

Good afternoon, after having been developing a blockchain web app for some months, it's the first time I get this error when making a transaction.

ValueError: {'code': -32000, 'message': 'only replay-protected (EIP-155) transactions allowed over RPC'}

This is my code. It has always worked, and I guess it's not a matter of code, it might be just a matter of Web3, but I'm asking just in case. Thanks in advance.

tx = {
    'nonce': nonce,
    'to': account_2,
    'value': web3.toWei(float_amount, 'ether'),
    'gas': 21000,
    'gasPrice': web3.toWei(50, 'gwei')
}
signed_tx = web3.eth.account.sign_transaction(tx, private_key)
tx_hash = web3.eth.send_raw_transaction(web3.toHex(signed_tx.rawTransaction))
1
  • 1
    I don't know much about py but can you add the chain Id somewhere in the config of your project like we do in truffle :/ or try to call the chain Id and see if you get a value
    – Majd TL
    Mar 9, 2021 at 16:13

2 Answers 2

26

You'll need to add chainId to your transaction object to save your tx from being replayed on other chains.

tx = {
    'chainId': 3, // for ropsten
    'nonce': nonce,
    'to': account_2,
    'value': web3.toWei(float_amount, 'ether'),
    'gas': 21000,
    'gasPrice': web3.toWei(50, 'gwei')
}

Check here for chain IDs of all EVM based chain

1
  • 2
    You just saved my life. Thank you so much man
    – Busto
    Mar 9, 2021 at 16:58
5

Another bypass is to run the node using --rpc.allow-unprotected-txs. It is helpful especially in cases where you can't specify the ID.

2
  • This worked for me. But is this option unsecure? Nov 11, 2022 at 17:14
  • RPC is necessary but I'm asking about that is sending non EIP155 transactions from RPC unsecure? Nov 12, 2022 at 9:49

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